FR2557172A1 - PREFABRICATED CIVIL ENGINEERING STRUCTURE, APPLICATION TO THE CONSTRUCTION OF A STRUCTURE AND STRUCTURE THEREOF - Google Patents

Abstract

System for the construction and utilization of multitubular structures called modules A, whose joined elements (2) have a cylindrical or prismatic shape. The dimensions (L, l) transversely to the axis (X-X) of the elements (2) are greater than the dimension (h) along this axis (X-X). Several joined modules constitute a line of modules, used to close off a river. Several lines of modules can be superimposed to build an overspill structure of a certain height. Structure is provided to float a line of modules into place above its sinking site. Modules can also be used advantageously for certain works built on dry ground.

Description

2557 172

  The present invention relates to a structure

  of prefabricated civil engineering, its application to construction

  tion of a work, and the work resulting therefrom such as a cut off of a stream of water, a dam, a lockstone of a lock, a sea dike and the like. The prefabricated structure targeted by the invention, of multitubular nature, as will be seen, will be for

  more simplicity called "organ" in the description

and the claims which follow.

  We know that to make a cut, that is to say a structure established across a stream of water going from one bank to another in order to raise the water level upstream, a process known is to operate simultaneously over the entire width of the water stream and progressing from the bottom to the surface. We then realize this

  which is called a horizontal cut.

  We also know that when making such a cut, the slope of the downstream facing of the massif increases with the weight of the riprap used and it follows that the length and volume of the massif decrease in

the same conditions.

  In addition, when making a cut, we seek to distribute the materials evenly over the entire length of the block to avoid the formation of a low point. Indeed, the erosion force increases with the depth of water and a local lowering of the

  crest of the massif therefore tends to increase this erosion force

  if we. We are then in the presence of an unstable phenomenon

  and if the arrival of the materials that are poured out to enhance-

  if the low point is too slow, these materials are

  tees and come to settle on the downstream slope, erosion continuing in this case until the downstream slope of the cut massif has become very low. It is therefore necessary to implement a very large volume of riprap

  to restore the initial level of the massif.

  However, the regular placement over the entire width of a stream of water of very heavy masses, whether natural riprap or artificial riprap such as precast concrete blocks, presents great difficulties. . Indeed, the simultaneous or almost simultaneous routing of heavy armourstone along the entire cutoff line is very difficult to achieve and generally requires the implementation

very expensive facilities.

  One of the aims of the present invention is to

  read an assembly constituting a heavy indivisible mass, capable of economically replacing a concrete mass acting by its weight, this assembly being arranged so as to constitute a structure such as a cut, a dam, a bridge abutment, a bajoyer of lock, or

  analogous, which is not moved, even by a violent current

  slow. Another object of the invention is to produce a structure which can be several tens of meters high and weighing several hundred or thousands of tonnes, while using only small quantities

  of a noble material such as steel.

  In order to achieve these goals, there is provided according to the invention a civil engineering structure called "organ" characterized in that it comprises several associated rigid tubular elements which are integral with each other and

  having filling openings.

  Thus, each organ, made of sheet steel or

  made of a similar material, constitutes a volu-

  light but light that can be put in place easily.

  In addition, the structure produced with one or more associated organs is substantially horizontal and can be filled

  gradually with a heavy material.

  According to an advantageous embodiment, the elements

  tubular are associated in at least one row extending

  dant transverse to the axis of the elements and the dimensions

  sions of the organ transverse to the axis of the elements are greater than its dimension along this axis. Thus the assembly has a very great stability when it is

put in place.

  According to a particular embodiment, the tubular elements are straight cylinders based

  circular, this arrangement allowing slight deformation

  mation of tubular elements during introduction

riprap.

  According to another advantageous alternative embodiment of the invention, the tubular cylindrical elements have a triangular base and the structure is made easily by a combination of sheets folded in zig zag associated with flat sheets. In particular, the sheets folded in zig zag consist of a succession of sheets in W placed end to end, separated by parallel flat sheets, the cell assembly thus produced being completed by plating sheets extending along

  of the organ and constituting the walls thereof.

  According to still other characteristics of realization

  tion of the invention, each organ has means

  to temporarily float on the water.

  Preferably, these means comprise inflated balloons arranged inside the tubular elements, or membranes stretched across the opening of the elements. These flotation means are preferably arranged at the base of the tubular elements so that the organ has a shallow draft when it floats. A way

  of simultaneous rupture of all the buoyancy means

  sound, for example an explosive primer placed on each membrane or each balloon, and triggered remotely is also provided to allow rapid stranding of the organ on the site of implantation of the cut by deletion

brutal means of flotation.

  By way of example, the process for producing a cut-off comprises the following steps: a rock-based plinth is produced having a substantially flat surface over the entire width of the water current, a line of organs is stranded on this plinth comprising at least one organ so that the tubular elements of each organ are arranged substantially vertically, the tubular elements of each organ are filled with

heavy materials.

  According to an advantageous version of the conforming process

  to the invention, each organ is floated to-

  above the grounding site and we cause this grounding while keeping the axes of the elements substantially vertical

  tubular by a simultaneous rupture of the means of flow-

  taison over the entire surface of the organ line. In particular, there is a floating organ line extending substantially over the entire width of the course

  of water by putting several organs end to end and ensuring

  throwing these between them. The floating organ line thus produced is retained by mooring cables

  wound on winches placed upstream of the dumping site

  and let it drift under the effect of the current by controlling the progress of the moorings until

  the line of organs is directly above the grounding site.

  Finally, the balloons are punctured simultaneously

or membranes.

  Such a process allows the realization of a structure such as cutting off a water stream even when the

  watercourse is not in a period of low flow.

  According to other characteristics of the method, successively several rows of organs, each row of organs being filled with heavy materials before the establishment of the next row of organs; an embankment is carried out upstream of each organ line after filling and the successive organ lines are stranded offset from one another upstream from the base of the cut-off,

  the whole thus having the appearance of a staircase.

  According to one aspect of the invention, there is provided a structure comprising at least one organ, the tubular elements of the organ being arranged in a substantially

  vertical and being filled with a heavy material.

  According to an advantageous variant, a work comprises several organ lines, at least partially superimposed, an embankment being produced on one side of each organ line, and the organ lines situated at different levels being offset by one

compared to others.

  Other features and advantages of the

  vention will result from the following description of examples

  non-limiting, with reference to the accompanying drawings in which: - Figure i is a perspective view of an organ cut-out according to the invention arranged in a dry stream; - Figure 2 is a partial top view of two organs comprising tubular elements with a triangular base; - Figure 3 is a diametrical sectional view of a tubular element with a circular base equipped with a buoyancy means (not cut) and arranged on a body of water, - Figure 4 is a top view of a tubular element in the shape of a triangular prism equipped with a buoyancy means, - Figure 5 is a schematic top view of a stream of water in which three associated organs are being set up; - Figure 6 is a schematic sectional view of a stream during the establishment of a first line of organs; - Figure 7 is a schematic sectional view of a stream during the establishment of a second row of organs; - Figure 8 is a schematic sectional view of a watercourse comprising a cutoff according to the invention, Figure 9 is a perspective view of an organ comprising cylindrical tubular elements with circular base, - Figure 10 is a schematic sectional view of a dam made with organs according to the invention, - Figure 11 is a sectional view of a cut including an alternative embodiment of the organs, - Figure 12 is a sectional view of 'a stream during the establishment of an organ line, according to an alternative embodiment, - Figure 13 is a sectional view of an alternative embodiment of a cut, - Figure 14 is a schematic sectional view of a seawall, - Figure 15 is a schematic sectional view of a quay wall, - Figure 16 is a schematic sectional view of the locks of a lock, - Figure 17 is a schematic sectional view of a scour pit downstream of a dam, - Figure 18 is a schematic sectional view

partial of a navigation channel.

  There is shown in Figure 1, in a perspective view, an organ A according to the invention placed in a watercourse B assumed momentarily dry. To ensure the setting of the organ A, the banks C of the water current have been arranged so as to produce a channel of substantially constant width and a height sufficient to contain the watercourse in periods

high water.

  At the cut-off, the banks C are supported by metal sheet pile curtains 1. In this embodiment, the organ A comprises a series of tubular elements 2 cylindrical parallel to each other, with circular bases joined together

  to others and welded together along generators.

  Each tubular element can for example be made from a steel sheet 3 mm thick, 2 meters high and 4.41 meters long, making it possible to produce a cylinder 1.5 meters in diameter by bending. sheet metal and welding of the two extreme edges brought into contact with each other. In the example considered, the organ A comprises several rows of tubular elements 2 joined together in parallel, the rows extending transversely to the axis XX of the elements 2 and constituting an indivisible structure whose dimensions (L, 1) transversely to the axis XX of the elements are greater than the dimension (h) along this axis. On the organ shown, all the elements have the same length and the organ therefore has substantially the shape of a parallelepiped whose long side is arranged perpendicular to the banks C. The tubular elements 2 are open at their two ends

  which are located in two parallel planes, ortho-

gonals to the axes of these elements.

  In the case of placement in a course

  momentarily dry, the organ can either be

  trout on a bank of the watercourse then put in place by appropriate means, or directly built in the bed of the watercourse. Once the organ is placed in the stream, the cylindrical elements are filled with

  heavy materials such as stones.

  Thus, even if the tubular elements 2 are not all completely filled, the weight of the assembly is sufficient to keep the organ in place in the stream and this organ has a substantially horizontal upper edge transversely to the stream of water so nowhere is there an acceleration of the water current

  likely to cause disorders.

  Tubular elements with a circular base present

  have the advantage of not deforming when they are filled with heavy material. But in the case of a cut made with an organ according to the invention, deformations, even quite significant, do not present any significant drawbacks and it is possible to replace the cylinders with circular base by. prisms, in particular with a triangular base allowing an easier realization of the organs. FIG. 2 shows a top view of an organ comprising tubular elements of this type

  forming a bundle of prismatic elements with a triangular base

  laire. The organ is then constituted by a series of flat sheets 3 between which are arranged zig zag sheets, and more particularly sheets 4 in W connected to the flat sheets by weld beads 5. In this case, the folded sheets can be brought to the site

already folded.

  There is shown in Figure 2 a partial view

  of two adjacent organs with complete ends

  7 and 8. It can be seen that these ends 7 and 8 can either rest directly on the banks of a watercourse, or fit one into the other so as to create a line of organs. exhibiting a certain rigidity. The rigidity of a line of associated organs can be increased by providing additional means of association such as welded legs joining

  the flat faces of two adjacent organs or cables 32.

  If an organ is subjected to a certain bending force, it is advantageous to replace the thin external sheets, or at least one of the sheets of the organ which play the role of sole of a beam working on bending,

  by thicker sheets 3a (fig. 2).

  According to another aspect of the invention, and in order to implement a row of organs in running water, provision is made according to the invention to equip the organs with temporary flotation means. In a preferred embodiment, these flotation means, as shown in Figures 3 and 4, are balloons

  9 made of an expandable plastic material such as rubber

  chouc or neoprene, comprising an inflation valve and a means for destroying the envelope, such as an explosive primer 11 which can be electrically controlled by means of a wire 12 connected to a firing member

  appropriate, or by any other means.

  Experience shows that it is not necessary to inflate the balloons 9 strongly to obtain friction

  sufficient for any risk of slipping to be eliminated.

  In particular, in the case of tubular elements with a triangular base, as shown in FIG. 4, the contact between the wall of the balloon 9 and the folded sheet 4 takes place along only part of each side of the triangle but ensures nevertheless sufficient friction to support the lifting force of the corresponding tubular element. In fact, when a balloon 9 is placed in each tubular element 2, the weight to be supported by the balloon 9 is minimal. On the contrary, the friction between the wall of the balloon 9 and the sheet 4 can, if desired, be considerable: it suffices for this to strongly inflate the balloon 9. The balloon 9 is preferably placed at the base of the element tubular, as shown in Figure 3, and thus ensures buoyancy with a minimum draft of the organ, when it is arranged

in the water stream.

  Note that it is not essential to provide all the tubular elements 2 with balloons. In fact, buoyancy is ensured by the immersion of only part of the balloon. As soon as a reduced number of balloons ensures the buoyancy of an organ, the other tubular elements can remain empty. However, it is preferable to provide a balloon in each element because this arrangement makes it possible to obtain the minimum draft. Although the preferred means of flotation is a balloon, provision is also made according to the invention for other

  means for ensuring the temporary flotation of the organ.

  In particular, the base or the top of the tubular elements 2 can be temporarily closed by means of a membrane

  flexible (sheet of plastic) or rigid (sheet).

  It is also possible to provide a floating belt placed outside the organ and held against it by any suitable means, the preferred objective being to be able to simultaneously remove all of the means of flotation of the organs so that they be submerged

  together as will be seen later.

  When building the organs, it is possible to

  ble to build a dry dock on the edge of the watercourse on which we must operate.

  its raft be either at will, sometimes dry and sometimes covered

  green of a few decimetres of water. When the soldering of an organ is completed, its buoyancy is ensured, for example by placing the balloons. In the case where balloons are used, these must be

  set up and inflated to the pressure ensuring a frot-

  enough while the organ is still dry,

  otherwise the balloon would rise in the tubular element

  area 2 as soon as the organ is put in the water and does not fill

  no longer functions. Indeed, if one inflated a balloon envelope which would be submerged, it would rise to the surface of the water from the start of the operation,

  that is to say before the balloon has taken on a sufficient volume

drying to rub on the walls.

  The water is then allowed to enter the refit block so that the organ can be evacuated to the watercourse. The dry dock is then dried to conveniently undertake the construction of the next organ. According to another embodiment, there is provided a submersible pontoon comprising ballasts and moored along a bank. When an organ has been built and equipped with its means of flotation, water is admitted into the ballasts and the pontoon is slightly submerged, its sinking being limited by chains moored to the shore and to independent floats After evacuation of the organ, the water is again removed from the ballasts and the pontoon emerges, ready for the construction of a

new organ.

  FIG. 5 shows a diagrammatic view

  tick above a watercourse on which three associated organs 13 equipped with their means of flotation are kept upstream of the abutments 14 between which the cutting must be carried out. Upstream of the abutments, the width of the watercourse must be greater than the abutment spacing so that the organs can be aligned and assembled. In order to avoid drift in the current, symbolized by an arrow F, cables are fixed at one end to bollards 20 secured to the organ, the cables being moreover wound on winches 16 arranged on the bank of the course d or on temporary platforms

  emerged 17, carried by piles beaten in the river.

  The organs 13 are thus kept in line to produce a floating line of organs D, of substantially length

  equal to the distance between the abutments 14.

  For its installation, we allow paral-

  in line with itself the floating line of organs D following F under the effect of the current by giving slack to the moorings 15, until the line of organs comes in Dl above the immersion site, after which we die simultaneously

all the balloons.

  Referring now to Figure 6 which shows a schematic sectional view of a stream at the time of making a cut. A base 18 is firstly placed on the bottom of the stream between the banks not shown. This base 18 is constituted by riprap of sufficient size

  so as not to be dragged by the current.

255717.

  The base 18, must extend downstream of the stranded organs so that the water flowing over their crest

  does not risk causing scouring.

  The horizontality of the base 18 is checked by means of a device called a "guillotine" comprising a horizontal bar carried by two uprights, each of which can pivot in a vertical plane. Where

  takes place, the necessary local recharges are carried out.

  To flatten the riprap surface, we use before-

  a sort of harrow moved by cables.

  Once the base 18 is produced, one or more organs 13a in line are brought into line with the base 18

by slackening the moorings 15.

  When the organ layer 13a is plumb

  of the base 18, the flotation means are destroyed simul-

  temporarily. In particular, experience shows that during the piercing of an inflated balloon, there is no progressive deflation but a real explosion of the balloon, the tear initially started being prolonged with very high speed. The line of organs immerses quickly while remaining horizontal until the base of the tubular elements 2 comes into contact with the surface of the base 18. The line of organs 13a then creates a dam with horizontal crowning over the entire width of the course

  water and tubular elements 2 can be progressed

  sively filled with a heavy material. The filling of the tubular elements 2 of the organs can be carried out by any suitable means by means of a suction dredge taking directly from the bed of the watercourse,

  small rip-raps that have been previously supplied

  blows or by pontoon-cranes unloading barges containing the necessary materials, or by a blonde. One would have feared that the organs, even filled with rockfill, would be dragged by the current by causing the rockfill in the base to roll under them. The experience

showed that it was not.

  We could not make a cut of a significant height with a single line of organs. According to a form

  After completion and filling, provision is made

  wise of a first row or layer of organs, to arrange in the same way a second row of organs above the first, the second row of organs being a little longer than the first if the valley has a section in V. To avoid scouring of the bed of the stream downstream of the cut, it may be preferable to divide the height of the fall into a series of elementary falls offset from each other

from upstream to downstream.

  This series of elementary falls is obtained as shown in Figure 7 by making an embankment 19 upstream of the first line of organs

  13 after filling thereof with riprap.

  The embankment surface extends upstream the upper surface

  of the first line of organs and then constitutes a receiving surface for a second line of organs 13b placed, stranded and filled in the same way as the first line of organs. A new backfill can be made upstream of the second row of organs and the structure shown in FIG. 8 is then obtained by adding a third row 13c, these various rows 13a, 13b, 13c being offset relative to each other. to others from the base of the cut to its top. It is thus possible to superimpose a series of organ lines and make a cut that significantly raises the level of the watercourse and thus even make a dam. On its upstream face, this dam preferably comprises a sealing coating, for example a

clay mass 46.

  When the dam is finished, the flow can

  to flow while passing over its crest.

  It will often happen that a water intake, intended for example to supply a hydroelectric plant is

  located at a level lower than the level of the crest of the structure.

  By suspending the work during large waters, the upper part of the structure can be built

dried up.

  In the variant of Figure 9, the organ further comprises a wire mesh 23 serving as a path

traffic.

  The organ finally has V-shaped scarves 24 arranged in the upper plane of the organ and fixed

  to the tubular elements, for example by welds.

  The scarves 24 thus distribute over several elements

  tubular 2 the forces supported by the mooring bollards

rage 25.

  Such scarves are not necessary with organs with triangular elements, the force exerted at a node being directly transmitted to six sheets which ensure a good distribution of the forces in the mass

of the structure.

  In an alternative embodiment o several organ lines are superimposed, if bollards 20 or 25 are used to retain the organs before they are stranded, these bollards can be placed back from the edge of the organ as is see in Figures 2, 5, 6, 7, 8, 9. These bollards also play

  the role of stop as seen in Figure 8.

  There is shown in Figure 10 a schematic sectional view of a dam made with organs

according to the invention.

  The dam has a series of organs. 13 super

  placed and offset from each other.

  A crown was made at its upper part

  nement constituted by a concrete slab 29 on which is disposed a movable barrier 30. The question of dimensions in height and

  width of the various stair treads is important.

  It is indeed desirable that the flood water flows without accelerating on the downstream facing of the structure. Under such conditions, it will be possible to dispense with providing an energy dissipating device downstream. It is however desirable that the last steps are

  drowned below the level of the downstream reservoir.

  Optionally, the steps have different widths, in particular the bottom steps can have a width E greater than that of

  top steps, as shown in Figure 10.

  Alternatively, the organs have progressive-

  an increasing height from the bottom to the top of the structure so that the slope of the downstream facing

  increases as the structure rises. The materials for the realization of the organs can be various. In

  in particular, to avoid corrosion problems, the steel sheets can be metallized or even be produced with a

slightly oxidizable steel.

  According to a variant, a concrete covering is also provided on the steps in order to prevent the water falling from the upper floor from carrying part of the materials which fill the organs, but it is then desirable to provide vents 22 allowing drainage of the organ lines and avoiding pressurization of the concrete coating by the water rising through the organ lines. Alternatively, the filling of the upper part of the constituent elements of the organs is carried out with sufficiently heavy riprap,

  some being joined by concrete.

  In the variant of FIG. 11, each of the organs of the organ lines 13a, 13b and 13c comprises three rows of elements 2a, 2b and 2c of similar height and

  a row of 2d elements of lower height which

  thus read, on the upper surface of the organ, a

  step 32 extending along the upstream edge of the organ.

  When placing the organs, the edge

  lower downstream of each organ comes to rest on the

  chement 32 of the organ arranged on the immediately lower stage, so that the result of the forces to which the organ is subjected, is directed substantially along the line joining the base of the recesses 32 and which

  is shown in dotted lines in FIG. 13.

  The slope of this line can be varied by varying the ratio of the number of rows of tall elements 2 to the number of rows of taller elements 2 or by varying the depth

of the dropout.

  In addition, the recess 32 constitutes a stop similar to the bollards 20 and therefore facilitates the establishment

  successive organ lines according to a perfect set

fully aligned.

  An alternative embodiment of the placing method

  in place described with reference to Figures 6 to 8 is shown

  felt in Figure 12. The section is partially truncated to allow a representation of the elements involved in the variant while remaining within the limits of the figure.

  According to this variant, the organs are previously

  nicely assembled online as before. However,

  the winches 17 are this time mounted on the organs themselves

  same. The end of the cables 15 opposite to that fixed on the winches 17 is provided with a hook 33 engaged in a loop 34 secured to a dead body 35 such as an organ according to the invention stranded and filled with riprap upstream of the clipping site. In the same way as before, when the organs are aligned according to a floating dam across the stream of water, slack is given to the cables 15

  to bring the organ line directly above its stranded area

  age. The organs are then kept at the desired level by means of pliers 36 fixed on them and which tighten the cables 15. The winches 17 are then dismantled and brought back

  on the ground then the organs are stranded and filled with water

  in the same way as before. After anchoring the organs, the cables 15 can be recovered or, on the contrary, left in place to constitute anchor rods as shown in FIG. 13. According to this embodiment, as and when the lines are put in place organs 13a, 13b and 13c, these were connected to an organ 35a previously stranded and filled with riprap and each of the retaining cables, respectively 15a to 15c, was held in place so that the lines of organs 13a to 13c are stabilized in position not only by the weight which acts on them but also by the traction on the cables 15 to 15c connected to the dead bodies 35a and 35b. To avoid an excessive angle of the cables 15 with the horizontal, it is advantageously provided that after having laid several organs, the upstream embankment is extended to the first dead body 35a 2 5 5 7 1i 72 which is thus integrated into the work, before setting up a second dead body 35b connected to the organs 13d to

  13f using lSd to 15f cables respectively.

  This alternative embodiment makes it possible to construct structures having a downstream face having a very large

  slope without risk of landslide.

  In the embodiment of FIG. 13, we also have

  Mention is made of a series of sheet piles 37 battered in the ground directly above the downstream edge of the lower organ line and which constitutes a surge arrester screen opposing a

scour of the structure.

  FIG. 14 shows the embodiment according to the invention.

  tion of a sea dike of the type that can be used

for tidal factories.

  In this case, the identical organ lines 13a to 13c are arranged in a staircase symmetrically with respect to the dike to cover it, an organ line 13f forming the final cover at the top of the dike. Thus, it is possible to make a dam by using a very loose material such as sand, this dam having despite this flanks having a steep slope and consequently reducing the volume

total of the dike.

2557172-

  The same replacement of a very soft slope by an organ staircase is indicated when one is brought to build an artificial island. Indeed, in this case as in that of the dam, we seek to reduce as much as possible the volume of sand used. FIG. 15 illustrates the embodiment according to the invention of a vertical quay wall exposed to a direct attack from the sea. The rapid variations in water in front of the vertical wall cause the production of very violent horizontal currents in front of the structure so that fatal scour to the stability of the wall itself

can happen there.

  In the case shown, a series of organ lines 13a to 13g are superimposed with one of their edges perpendicular to the others in order to constitute a continuous vertical wall 51. According to the advantageous embodiment shown, the wall is extended towards the wide by a paving 52 formed of rows of 13h to 13k organs arranged on the bottom of

  the sea next to each other at the same level and

  killing indivisible masses of several hundred

  tons comforting each other.

  To build (figure 16) a lock comprising two vertical bajoyers 39 and 40, one can use organs with triangular elements as described with reference to FIG. 2. The visible face of a bajoyer consists of adjoining rectangular sheets. The construction of the structure being assumed to be done dry, it is inexpensive to weld the sheets together to obtain a perfectly sealed structure. In this case, it is preferably chosen for the production of organs, a steel grade particularly resistant to rust and wear produced by the friction of boats. To better resist the shocks of these, inevitable, especially near the heads, the elements located immediately in contact with the sheets constituting the facing could be filled

  with concrete and not with heavy materials.

  Figure 17 is the cross section of the downstream portion of an overflow structure 42 and the pit

* 43 scour which usually follows.

  It is in this pit, the depth of which downstream from certain natural waterfalls, reaching a hundred * meters, that the energy produced by the fall dissipates in vortices. A similar phenomenon of scouring occurs

  produced downstream of certain dams.

  To limit the deepening of the pit,

  this is sometimes entirely covered with masonry.

  In other circumstances its deepening is

  sometimes limited by the use of very large riprap.

  In the context of the present invention, the bottom of the pit 43 is protected by a paving 44 comprising one or more rows of organs joined in a layer near the structure 42 followed by one or more organs 46 in ascending staircase which break the current so that it is no longer in torrential regime at the outlet

of the scour pit 43.

  FIG. 18 illustrates the construction of a navigation channel 53, the banks of which are protected against the movement resulting from the passage of boats by a

  continuous line of organs 13 embedded in bank 45.

  The above nonlimiting exemplary embodiments show that the prefabricated civil engineering structure in accordance with the invention lends itself in a simple manner to the constitution of very numerous works,

  remarkable for the simplicity and speed of the edifi-

  cation, robustness and low cost of the means put

in action.

  Among the uses that it was not considered essential to represent by figures, one can quote the use of one or more rows of organs to constitute the type of work called bottom threshold We know that following modification by

  engineers of the plan layout of certain watercourses,

  such as shortening the route to the concentration of water in a single bed, the bed may deepen. A continuous deepening is notably noted on certain non-channeled portions of the course of the Rhine. It is sometimes recognized that it is necessary to combat this phenomenon, which would risk continuing for

  tens or even hundreds of years.

  The construction of bottom thresholds is one of the

  processes that can be used.

  A few rows of organs from one bank to the other

  the other from the river would constitute a very economical remedy.

  It is not excluded that we can, in such a case,

  dispense with filling the cells with weighted materials

  reux, the solid flow of the watercourse being able to carry out, at least partially, such a filling Of same, it is possible that one is brought, so much for: r protecting the bottom of a course of water, only to carry out different works at sea, to spread on the bottom a carpet of organs. The realization of such an operation would be particularly simple and it could comprise the following stages:

  - we will start by building the carpet together

  rigidly blocking each other, a number of organs floating on the surface of the water. A certain number of cells will be completely filled with balloons,

  while the others will remain free.

  - In the free cells, there will be a certain number of masses, each of them being retained

  by a rope terminated by a hook fixed to the upper part

laughter of a sheet.

  - A number of retaining cables will be used, for example at the four corners of the carpet, if it has a rectangular shape. Total immersion occurring after

  installation of a sufficient number of ballast masses.

  We will control it with cables.

  - As the descent, the volume of the balloons will decrease due to the compression of the balloons by the increasing pressure of the water, so that we will have to cut a certain number of ropes

supporting the ballast.

  When the carpet is at a short distance from the supposedly rough horizontal bottom, it will have to be brought

  above its exact grounding location. This opera-

  tion will be very simple, because it will be done without rubbing-

  like moving a boat in calm waters.

  Frogmen will also have the possibility of using small underwater engines similar to those

  that they are used to using when traveling.

  The present invention is not limited to

  examples of embodiments which have been described but is suscep-

  tible of variants that will appear to those skilled in the art.

  In particular, the tubular elements may have

  various shapes, for example square or hexagonal sections

  nales. Although the invention has been described in connection with substantially straight organs, it will be understood that the tubular elements can be combined so as to produce bent organs in top view, so that a bent cut will be produced and a certain effect

voting will then be obtained.

Claims (28)

  1. Civil engineering structure called "organ" (A) characterized in that it comprises several rigid tubular elements (2) associated forming a body with one another and comprising filling orifices. 2. Organ according to claim 1 characterized in that the tubular elements are associated in at least one row extending transversely to the axis (XX) of the elements (2), and in that the dimensions (L, 1) of the organ transversely to the axis (XX) of the elements (2) are greater than its dimension (h) along this axis (X-X).   3. Organ according to claim 1 or the   claim 2 characterized in that the tubular elements   laires (2) are attached to each other.   4. Organ according to one of the claims   1 to 3, characterized in that the tubular elements   (2) are cylinders of revolution.   5. Organ according to one of the claims   1 to 3, characterized in that the tubular elements   (2) are triangular prisms.   6. Organ according to claim 5, charac-   terized in that the tubular prismatic elements (2) comprise sheets bent in a zig zag (4) arranged between flat sheets (3).   7. Organ according to one of the claims   1 to 6, characterized in that at least one of its ends   lateral mites has a sinuous profile (7), intended to allow embedding with the end of an adjacent organ of complementary profile (8) to form a row of organs.   8. Organ conforming to any one of the res-   dications i to 7 characterized in that it comprises at least   a recess (32) on its upper surface.   9. Organ conforming to any of the claims   cations 1 to 8, characterized in that at least one of   walls (3a) has a thickness greater than the other walls.   10. Organ according to any one of the res-   dications 1 to 8, characterized in that it comprises means (9) for temporarily ensuring its flotation on the water.   11. Organ according to claim 9, charac-   characterized in that the flotation means comprise inflatable balloons (9) arranged inside the tubular elements.   12. Organ according to claim 9 or claim 11, characterized in that it comprises means (11) for ensuring the simultaneous rupture of   all the flotation means.   13. Organ according to claim 12, charac-   characterized in that the means for ensuring the rupture of the flotation means include explosive primers   (11) arranged on the flotation means and triggering from a distance.   14. Method of making a work in   by means of at least one organ (A) conforming to one of the resales   dications 10 to 13, characterized in that it comprises the following stages: - a base (18) is produced having a substantially flat surface over the entire width of the stream of water - a line d on the base (18) 'organs (13) comprising at least one organ so that the tubular elements (2) of each organ are arranged substantially vertically; - the tubular elements (2) are filled with   each organ with heavy materials.   15. Method according to claim 14,   characterized in that each organ (A, 13) is brought to-   above the grounding site and cause this grounding while keeping the axes of the tubular elements substantially vertical by a simultaneous rupture of the floating means   taison over the entire surface of the organ line.   16. Method according to claim 15,   characterized in that a flow line organ is produced   aunt (D) extending substantially over the entire width of the stream by placing several organs end-to-end   (13) and subjecting them to each other.   17. Method according to claim 15 or 16, characterized in that the organ or all of the organs joined together, constituting the line of floating organs (D) is arranged transversely to the current and retained by moorings (15 ) wound on winches (16) placed upstream of the grounding site and in that the floating line of organs (D) is allowed to drift under the effect of the current by controlling the course of the moorings (15) up to the floating organ line is directly above the grounding site.   18. Method according to one of claims 14 to   17 characterized in that several rows of organs (13a, 13b, 13c) are successively deposited so as to bring them at least in part to each other, each row of organs being filled with heavy materials before placing in   place of the next row of organs.   19. A method according to claim 18, characterized in that an embankment (19) is made upstream of each organ line after the filling thereof and in that the successive organ lines fail ( 13a, 13b, 13c) offset from each other to others.   20. Method according to one of claims   14 to 19 characterized in that after the grounding and the filling   organ sage, part (21) of the upper extremities   free tubular elements (2) is concreted.   21. Work comprising at least one organ according to   any one of claims 1 to 13 characterized   in that the organ extends from one end to the other of the structure, the tubular elements (2) of the organ being arranged substantially vertically, and being filled of a heavy material.   22. Work according to claim 21 characterized in that it comprises several organ lines   (13) at least partially superimposed.   23. A work according to claim 21 or to claim 22 characterized in that it comprises   a movable dam (30) disposed at its top.   24. Work conforms to any of the   claims 21 to 23 arranged across a course   of water, characterized in that it has a coating   seal (46) on its upstream face.   25. Work conforms to any of the   claims 21 to 24 characterized in that it comprises   a arrester (37) extending below the dimension   of foundation of the lowest organ (13).   26. Work conforms to any of the   claims 21 to 25 characterized in that it comprises   around it a paving (52) consisting of a set adjoining organs (1 p.m. - 1 p.m.).   1 27. Work conforms to any of the   Claims 21 to 26 characterized in that it comprises   cables (15a - 15f) tensioned between the organs and dead bodies located upstream relative to the thrust of the water, these cables (15a, 15f) and these bodies   dead (35a, 35b) being drowned in the body of the work.   28. A work according to claim 21, characterized in that it comprises several organs (13) comprising tubular elements (2) of metal in the form of triangular prisms, the organs being exactly superimposed and their side faces being welded together. along their edges to form a watertight continuous vertical plane.